"One of the kindest, most down to down, incredible human beings I have ever encountered," Delevingne captioned a photo of herself with Rieder. "You will be so missed by so many people. Ride and Rest In Peace Dylan Rieder."

Tony Hawk also paid tribute by sharing a video of Rieder skateboarding. "Thank you for making skateboarding so much better while you were here, Dylan," Hawk wrote. "Skating like this can't be taught; it is a product of passion, dedication and innate style. Dylan Rieder had all that and more. Do an impossible in his honor today while wishing you could do it like this."

In lieu of flowers, Rieder’s family has asked that donations be made in his memory to Dr. Stephen Forman, an international expert in leukemia, lymphoma and bone marrow transplantation from the City of Hope Cancer Treatment Center.